Energy bills as a percentage of income in the U.S. are at their highest point since 1987, according to a report in the Christian Science Monitor. Overall, they are still below the levels seen in the 70s and early 870s, but energy bills in some low income households is approaching 10 percent.

Polls show Americans believe energy prices will continue to rise.

"If it rises much more, it will become a significant problem, particularly for lower-income households," Mark Zandi, chief economist at Moody's Economy.com, told the newspaper.

While this is bad for the average consumer, high energy prices have been driving demand for solar energy and high mileage cars. Side note: gas costs more on hot days because of expansion. Congress is looking into the so-called hot gas phenomenon.

It's something to think about while filing up on the 4th of July holiday.